According to the present invention, a writing implement is engaged by a movable carrier. One end of the writing implement is fixed to the carrier/formed such as type type of three-quarters of the round. The carrier controls smoothly the movements of the writing implement when the carrier travels back and forth in response to the rotations of the cap. Because the supporting member of the cap is extended suitably along the inner side of the pencil barrel, it is possible that the circumference of the supporting member of the cap and the carrier makes always the annular member so that, when the cap is rotated, the supporting member induces the rotating force of the carrier. It is noted that the circumference of the carrier is approximately three-quarters of the round while the circumference of the supporting member is approximately a quarter of the round.
For example, when the cap is turned clockwise, the carrier moves forward along the inner spiral grooves of the pencil barrel because the carrier is rotated itself along the spiral grooves in response to the rotations of the cap. If the cap is turned counter-clockwise, the carrier moves back along the spiral grooves of the pencil barrel.
In a preferred form of the invention, the carrier controlled by the cap is engaged in the spiral grooves formed along the inside of the pencil barrel. Since the carrier is linked suitably in the spiral grooves by the spiral guide formed on the carrier, the carrier will move smoothly back and forth under the rotating force of the cap. The movement of the carrier provides a consequent smooth back and forth movement of the writing implement engaged with the carrier.
Because the cap has the protruding holder travelling along the rounded circular recess in the inside of the pencil barrel, the cap can be rotated itself always and also maintain a constant position.
According to the another embodiment of present invention, a double-ended pencil is provided in which a pair of the writing implements are controlled in their back and forth movements by the separate carriers moving along the separate spiral grooves controlled by the separate handles located at the both ends of the pencil barrel.
These and other aspect of the invention will be more fully understood by referring to the following detailed description and the accompanying drawings.